Property crime continues to be a major cost to economies worldwide. To combat crime, most businesses use security systems that detect, deter, document, deny, and delay intrusions into a protected area or facility. Security systems are particularly important in applications where government and/or private security personnel do not patrol or are otherwise not responsible for the area or facility.
A typical security system is an integrated system that typically includes a number of intrusion detection sensors, an alarm processor, an intrusion/alarm monitoring station, and a communications structure or network that connects these elements and connects the system to the reaction elements. In interior intrusion systems, a broad variety of sensor types is available for use. Examples include window sensors, glass break sensors, door sensors, wall sensors, volumetric sensors, beam sensors, video sensors, noise level sensors, and motion sensors.
A security system, whether providing security against exterior or interior intrusions, is commonly evaluated based on three performance characteristics, namely the probability of detection (PD), false alarm rate (FAR), and vulnerability to defeat. The PD provides an indication of sensor performance in detecting movement within a zone covered by the sensor. The FAR indicates the expected rate of occurrence of alarms which are not attributable to intrusion activity. Vulnerability to defeat indicates the likelihood that an intruder can bypass a sensor/security system without detection. A major goal of the security planner is to field an integrated detection system that exhibits a low FAR and a high PD and is not susceptible to defeat.
Although security systems are available that meet these objectives, they can be quite costly. The various components are expensive to install and commonly sold at a high cost. Although it is possible to use an existing installation such as a power line to transmit video for security monitoring, a substantial investment is still required for the security system. Ongoing charges are typically also assessed for monitoring and maintaining the security system components. Moreover, the components can be relatively obtrusive and unsightly and are generally used only for security activities.